DIFFERENTIAL EMISSION MEASURE ANALYSIS OF MULTIPLE STRUCTURAL COMPONENTS OF CORONAL MASS EJECTIONS IN THE INNER CORONA

Abstract

In this paper, we study the temperature and density properties of multiple\nstructural components of coronal mass ejections (CMEs) using differential\nemission measure (DEM) analysis. The DEM analysis is based on the six-passband\nEUV observations of solar corona from the Atmospheric Imaging Assembly onboard\nthe \\emph{Solar Dynamic Observatory}. The structural components studied include\nthe hot channel in the core region (presumably the magnetic flux rope of the\nCME), the bright loop-like leading front (LF), and coronal dimming in the wake\nof the CME. We find that the presumed flux rope has the highest average\ntemperature ($>$8 MK) and density ($\\sim$1.0 $\\times10^{9}$ cm$^{-3}$),\nresulting in an enhanced emission measure (EM) over a broad temperature range\n(3 $\\leq$ T(MK) $\\leq$ 20). On the other hand, the CME LF has a relatively cool\ntemperature ($\\sim$2 MK) and a narrow temperature distribution similar to the\npre-eruption coronal temperature (1 $\\leq$ T(MK) $\\leq$ 3). The density in the\nLF, however, is increased by 2% to 32% compared with that of the pre-eruption\ncorona, depending on the event and location. In coronal dimmings, the\ntemperature is more broadly distributed (1 $\\leq$ T(MK) $\\leq$ 4), but the\ndensity decreases by $\\sim$35% to $\\sim$40%. These observational results show\nthat: (1) CME core regions are significantly heated, presumably through\nmagnetic reconnection, (2) CME LFs are a consequence of compression of ambient\nplasma caused by the expansion of the CME core region, and (3) the dimmings are\nlargely caused by the plasma rarefaction associated with the eruption.\n